The use of chromogens as substrates to detect specific antigens is currently used by pathologists to diagnose biopsied tissue samples. The ability to detect multiple antigens in the same tissue section has the advantage of providing more validating data regarding the disease status of the patient. This can be critical especially when the amount of tissue is limited and multiple sections do not exist. Multiplexed detection allows one to study two or more antigens in the same cell; if the presence overlaps in space, this is known as co-localization. In order to detect this, two or more separate colors should be observed.